Resin-encapsulated semiconductor apparatus and process for its fabrication

ABSTRACT

The present invention provides a resin-encapsulated semiconductor apparatus comprising a semiconductor device having a ferroelectric film and a surface-protective film, and an encapsulant member comprising a resin; the surface-protective film being formed of a polyimide. The present invention also provides a process for fabricating a resin-encapsulated semiconductor apparatus, comprising the steps of forming a film of a polyimide precursor composition on the surface of a semiconductor device having a ferroelectric film; heat-curing the polyimide precursor composition film to form a surface-protective film formed of a polyimide; and encapsulating, with an encapsulant resin, the semiconductor device on which the surface-protective film has been formed. The polyimide may preferably have a glass transition temperature of from 240° C. to 400° C. and a Young&#39;s modulus of from 2,600 MPa to 6 GPa. The curing may preferably be carried out at a temperature of from 230° C. to 300° C.

This is a continuation application of U.S. Ser. No. 09/689,802, filedOct. 13, 2000, which is a continuation application of U.S. Ser. No.09/665,062, filed Sep. 19, 2000, which is a divisional application ofU.S. Ser. No. 09/012,104, filed Jan. 22, 1998, now U.S. Pat. No.6,147,374.

This application is based on application No. H9-9276 filed in Japan, thecontent of which is incorporated hereinto by reference.

BACKGROUND OF THE INVENTION

1. Field of the Invention

This invention relates to a resin-encapsulated semiconductor apparatushaving a semiconductor device with a ferroelectric film, and a processfor its fabrication.

2. Description of the Related Art

In recent years, non-volatile or large-capacity semiconductor memorydevices having thin films of ferroelectric substances (dielectricmaterials having a high dielectric constant, or substances having aperovskite crystalline structure) have been proposed. Ferroelectricfilms have features such as self polarization and high dielectricconstant characteristics. Hence, the ferroelectric films have hysteresischaracteristics between polarization and electric fields offerroelectric substances, and their utilization enables materializationof non-volatile memories. Also, the ferroelectric films have such alarger dielectric constant than silicon oxide films that memory cellscan be made to have a smaller area when the ferroelectric films are usedas capacitive insulation films, to enable materialization oflarge-capacitance highly integrated RAMs (random access memories).

The ferroelectric films are comprised of a sintered body of a metaloxide, and contain much oxygen which is rich in reactivity. Whencapacitors are formed by using such ferroelectric films in thecapacitive insulation films, it is indispensable, in the upper and lowerelectrodes of the capacitive insulation films, to use a substance whichis stable to oxidation reaction, as exemplified by an alloy chieflycomposed of platinum.

After capacitors, interlayer insulation films and so forth have beenformed, passivation films are formed on the outermost surfaces of thedevices. Silicon nitride or silicon oxide is used in the interlayerinsulation films and passivation films, which are usually formed by CVD(chemical vapor deposition) and hence hydrogen is often incorporated inthe films.

When semiconductor apparatuses making use of such ferroelectric filmsare used in electronic equipment for public use, they are required to beinexpensive resin-encapsulated semiconductor apparatuses having goodmass productivity. In particular, ferroelectric non-volatile memoriesare greatly needed for portable equipment as memories substituting flashmemories, because of their properties such as low power, low voltage,and non-volatility making refresh operation unnecessary, and theresin-encapsulated semiconductor apparatuses are also desired in orderto provide thin type packages.

At present, however, devices that utilize the ferroelectric films ascapacitive insulation films are chiefly held by ceramic-encapsulatedproducts, and almost no resin-encapsulated products are available.Devices with a large capacity are also not yet developed. This isbecause the polarization characteristics of ferroelectric filmsdeteriorate as a result of heat treatment.

Capacitors having ferroelectric films are known to undergo deteriorationof polarization characteristics upon their annealing in an atmosphere ofhydrogen (Lecture Collections in '96 Ferroelectric Film Memory TechniqueForum, published by K.K. Science Forum, Inc. Page 4-4). Thisdeterioration is presumed to be caused by the platinum of upper andlower electrodes which reacts with hydrogen to act as a reducingcatalyst to reduce the ferroelectric film. In particular, in the case oflarge-capacity highly integrated devices, the ferroelectric films arefine in size, and hence this deterioration of the characteristics of thecapacitors is forecasted to greatly affect the characteristics of theoverall devices.

In the resin-encapsulating of semiconductor devices by transfer molding,encapsulant resins containing fillers (usually silica) are used. Thefillers contained in encapsulant resins, however, have such hardparticles that the fillers may damage the device surfaces whenencapsulated. Moreover, since ferroelectric materials exhibitpiezoelectricity, the characteristics of ferroelectric films ma y changeupon application of a pressure to the ferroelectric film inside thedevices when encapsulated. In the fabrication of DRAMs (dynamic randomaccess memories), α-rays are emitted from radioactive componentscontained in the fillers, to cause memory soft errors in some cases.Accordingly, in order to prevent the device surfaces from being damagedby the fillers, to prevent application of pressure to the ferroelectricfilms and to screen α-rays being emitted from the fillers, protectivefilms comprised of polyimide must be previously formed on the devicesurfaces. Such surface-protective polyimide films are formed byheat-curing polyimide precursor composition films usually at atemperature of about 350 to 450° C. When such a polyimide precursor isheat-cured, the hydrogen contained in the passivation films orinterlayer insulation films may diffuse to cause a deterioration ofpolarization characteristics of the ferroelectric films. Thus, noresin-encapsulated products of devices in which thermoplastic resins areused as surface-protective films are known at present.

SUMMARY OF THE INVENTION

An object of the present invention is to provide a resin-encapsulatedsemiconductor apparatus having a ferroelectric film with goodpolarization characteristics and having a high reliability, and aprocess for its fabrication.

Studies made on conditions under which ferroelectric films cause thedeterioration of polarization characteristics have revealed that thedeterioration occurs when heated at above 300° C. The present inventorsthought that the surface-protective polyimide films could be heat-curedat below 300° C. However, when conventional polyimide precursors areused, which cure at such a low temperature, the resultantresin-encapsulated semiconductor apparatuses had a problem in theirsolder reflow resistance.

At present, as methods for packaging resin-encapsulated semiconductorapparatuses on printed-wiring substrates, face-down mounting isprevalent. The face-down mounting employs a solder reflowing method, inwhich leads of a semiconductor device and wiring of a printed-wiringsubstrate are provisionally joined with a cream solder followed byheating of the entire semiconductor device and substrate to solder them.As methods sorted according to how heat is applied, infrared reflowingand vapor phase reflowing are known, the former being a method utilizinginfrared radiated heat and the latter being a method utilizingcondensation heat of fluorinated inert liquid.

As encapsulant resin, epoxy resin is usually used. This epoxy resinalways absorbs moisture in an ordinary environment. At the time ofsolder reflow soldering, resin-encapsulated semiconductor apparatusesare exposed to high temperatures of from 215 to 260° C. Hence, when theresin-encapsulated semiconductor apparatuses are packaged on thesubstrate by reflow soldering, the abrupt evaporation of water causescracks in the encapsulant resin to bring about a serious problem in viewof the reliability of semiconductor devices. Accordingly, in the past,various improvements have been made from the viewpoint of making theencapsulant resin have a lower moisture absorption and have a highadhesion performance (Thermosetting Resins, Vol. 13, No. 4, published1992, page 37, right column, lines 8-23).

The present inventors have examined resin cracks produced inconventional resin-encapsulated semiconductor devices, and have foundthat peeling occurs at the interface between the devicesurface-protective polyimide film and the encapsulant resin, and thatthis is the starting point of causing cracks in the encapsulant resin.They have also found that this peeling is influenced by physicalproperties of surface-protective films, in particular, glass transitiontemperature and Young's modulus.

Now, as a result of further detailed studies, it has been found thatferroelectric films may cause less deterioration of polarizationcharacteristics when the device surface-protective polyimide films areformed by heat treatment in the temperature range of from 230° C. to300° C. It has been also found that, when the polyimide formed at suchheat treatment temperature has a glass transition temperature of from240° C. to 400° C. and a Young's modulus of from 2,600 MPa to 6 GPa, theresin-encapsulated semiconductor apparatus has a superior solder reflowresistance and no peeling may occur at the interface between the devicesurface-protective polyimide film and the encapsulant resin, promisinghigh reliability.

Based on these new findings, the present invention provides aresin-encapsulated semiconductor apparatus comprising a semiconductordevice having a ferroelectric film and a surface-protective film, and aencapsulant member comprising a resin, the surface-protective film beingformed of a polyimide. The present invention has first made it possibleto materialize such a device for the first time.

The present invention also provides a process for fabricating aresin-encapsulated semiconductor apparatus, the process comprising thesteps of;

forming a polyimide precursor composition film on the surface of asemiconductor device having a ferroelectric film;

heat-curing the polyimide precursor composition film to form asurface-protective film formed of a polyimide; and

encapsulating with a encapsulant resin the semiconductor device on whichthe surface-protective film has been formed.

The polyimide used in the present invention as a material for thesurface-protective film may preferably have a glass transitiontemperature of from 240° C. to 400° C. and a Young's modulus of from2,600 MPa to 6 GPa. Use of such a polyimide makes it possible to obtaina semiconductor device having a high reliability, without causing anycracks even by reflow soldering. The polyimide precursor compositionfilm may preferably be heat-cured at a temperature of from 230° C. to300° C., but may be done at a temperature higher than 300° C. so long asthe heat treatment is carried out at 350° C. or below for a short time(usually within 4 minutes, depending on the heat resistance ofsemiconductor devices) and also the polyimide film thus formed has aYoung's modulus of 3,500 MPa or above and a glass transition temperatureof 260° C. or above, thus the objects of the present invention can beachieved without causing any deterioration of polarizationcharacteristics of the ferroelectric film.

Incidentally, the fabrication process of the present invention may alsobe applied to resin-encapsulated laminates in which polyimide films areused for purposes other than surface-protective films, e.g., insulatingfilms.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a cross-sectional view of an LOC (lead on chip) typeresin-encapsulated semiconductor apparatus.

FIGS. 2A to 2F illustrate an example of a process for fabricating theresin-encapsulated semiconductor apparatus.

FIG. 3 is a cross-sectional view of a resin-encapsulated semiconductorapparatus fabricated in Example 1.

FIG. 4 is a cross-sectional view of a semiconductor device having aferroelectric film.

DETAILED DESCRIPTION OF THE INVENTION

As a polyimide precursor preferable in the present invention, which canobtain the polyimide having a glass transition temperature of from 240°C. to 400° C. and a Young's modulus of from 2,600 MPa to 6 GPa byheat-curing it at 230° C. to 300° C., it may include polyamic acidscomprised of a repeating unit represented by the following generalformula (I).

wherein R¹ is at least one of tetravalent aromatic organic groups shownin the following chemical formula group (II), and R² is at least one ofdivalent aromatic organic groups shown in the following chemical formulagroups (III) and (IV).

Of these polyamic acids, polyamic acids wherein R¹ is at least one ofthose listed in the following chemical formula group (VII) and R² is atleast one of those listed in the following chemical formula group (VIII)are particularly suited to the present invention.

In particular, those shown in the following chemical formulas (XIV) and(XVI) to (XVIII) are suited to the present invention. Of these, apolyamic acid comprised of a repeating unit represented by the chemicalformula (XVI) is most preferred.

The polyamic acid used in the present invention may further have, inaddition to the unit represented by the formula (I), a repeating unithaving the same structure as the one represented by the above generalformula (I) but having a siloxane group as R², so long as it is not morethan 10.0 mol % of the number of total repeating units. Here, thesiloxane group used as R² may be an aromatic siloxane group, and may beat least one of groups having the structure represented by the followingchemical formula group (VI).

The polyimide precursor composition can be formed into films by, e.g.,when the composition is in the form of a liquid or a varnish, coating orspraying the composition on the device surface, optionally followed byheating to bring it into a half-cured state (a state of not completelybeing made into imide). For example, a means such as rotary coatingusing a spinner may be used. The coating film thickness may be adjustedaccording to coating means, solid concentration of the polyimideprecursor composition, viscosity and so forth. When the polyimideprecursor composition is in the form of a sheet, it may be placed on orstuck to the device surface to form a film.

The surface-protective film often has openings formed in order to laythe underlying layer bare at the desired portions, e.g., at bondingpads. To form such openings, a resist film may be formed on the surfaceof the polyimide precursor composition film standing half-cured or thepolyimide film having been cured, followed by pattern processing by aconventional fine processing technique, and then the resist film may beremoved. When the openings are formed in a half-cured state, the patternprocessing is followed by heat treatment to completely cure the coating.

When the polyimide precursor composition is a photosensitivecomposition, the composition film may be exposed to light through a maskwith a given pattern and then the unexposed areas may be dissolved andremoved using a developing solution, followed by heat curing to form apolyimide film with the desired pattern.

Accordingly, the polyimide precursor composition used in the presentinvention may preferably be a photosensitive polyimide precursorcomposition containing the above polyamic acid and further containing anamine compound having carbon-carbon double bonds, a bisazide compound, aphotopolymerization initiator and/or a sensitizer.

The amine compound may specifically include, as preferred examples,2-(N,N-dimethylamino)ethyl acrylate, 2-(N,N-dimethylamino)ethylmethacrylate, 3-(N,N-dimethylamino)propyl acrylate,3-(N,N-dimethylamino)propyl methacrylate, 4-(N,N-dimethylamino)butylacrylate, 4-(N,N-dimethylamino)butyl methacrylate,5-(N,N-dimethylamino)pentyl acrylate, 5-(N,N-dimethylamino)pentylmethacrylate, 6-(N,N-dimethylamino)hexyl acrylate,6-(N,N-dimethylamino)hexyl methacrylate, 2-(N,N-dimethylamino)ethylcinnamate, 3-(N,N-dimethylamino)propyl cinnamate,2-(N,N-dimethylamino)ethyl-2,4-hexadienoate,3-(N,N-dimethylamino)propyl-2,4-hexadienoate,4-(N,N-dimethylamino)butyl-2,4-hexadienoate,2-(N,N-diethylamino)ethyl-2,4-hexadienoate and3-(N,N-diethylamino)propyl-2,4-hexadie noate.

Any of these may be used alone or in the form of a mixture of two ormore, and may be mixed in a proportion of from 10 parts by weight to 400parts by weight based on 100 parts by weight of the polyamide acidpolymer.

The bisazide compound may specifically include, as preferred examples,compounds listed in the following chemical formula groups (IX) and (X).Any of these compounds may be used alone or in the form of a mixture oftwo or more, and may be mixed in a proportion of from 0.5 part by weightto 50 parts by weight based on 100 parts by weight of the polymer.

As examples of the photopolymerization initiator and sensitizer, theyspecifically include, but are not limited to, Michler's ketone,bis-4,4′-diethylaminobenzophenone, benzophenone, benzoyl ether, benzoinisopropyl ether, anthrone, 1,9-benzoanthrone, acridine, nitropyrene,1,8-dinitropyrene, 5-nitroacetonaphthene, 2-nitrofluorene,pyrene-1,6-quinone-9-fluorene, 1,2-benzoanthraquinone, anthanthrone,2-chloro-1,2-benzoanthraquinone, 2-bromobenzoanthraquinone,2-chloro-1,8-phthaloylnaphthalene, 3,5-diethylthioxanthone,3,5-dimethylthioxanthone, 3,5-diisopropylthioxanthone, benzyl,1-phenyl-5-mercapto-1H-tetrazole, 1-phenyl-5-Mertex,3-acetylphenanthrene, 1-indanone, 7-H-benz[de]anthracen-7-one,1-naphthol aldehyde, thioxanthen-9-one, 10-thioxanthenone and3-acetylindol. Any of these may be used alone or in the form of amixture of two or more of them. The photopolymerization initiator andsensitizer used in the present invention may preferably be mixed in aproportion of from 0.1 part by weight to 30 parts by weight based on 100parts by weight of the polymer.

As an exposure light source used in the above patterning, which iscarried out by photolithography, any of ultraviolet rays, as well asvisible light rays and radiation rays, may be used.

The developing solution may include non-protonic polar solvents such asN-methyl-2-pyrrolidone, N-acetyl-2-pyrrolidone, N,N-dimethylformamide,N,N-dimethylacetamide, dimethyl sulfoxide, hexamethylphosphramide,dimethylimidazolidinone, n-benzyl-2-pyrrolidone, N-acetyl-ε-caprolactamand γ-butylolactone, any of which are used alone, and solutions of amixture of any of poor solvents for polyamic acid, such as methanol,ethanol, isopropyl alcohol, benzene, toluene, xylene, methyl cellosolveand water, and any of the above non-protonic polar solvents, either ofwhich may be used.

The pattern formed by development is subsequently washed with a rinsingsolution to remove the developing solution. As the rinsing solution, apoor solvent for polyamic acid, having a good miscibility for thedeveloping solution may preferably be used, and may include, aspreferred examples, the above methanol, ethanol, isopropyl alcohol,benzene, toluene, xylene, methyl cellosolve and water.

The heat treatment to heat-cure the polyimide precursor composition filmmay respectively be carried out by heating using a hot plate. Use of thehot plate enables imidation and film formation of polyimide precursormaterials in a shorter time than heat treatment employing a furnace suchas an oven furnace or a diffusion furnace. Thus, the time for heatingthe ferroelectric film can be made shorter.

The semiconductor device to which the present invention is applied mayinclude, e.g., non-volatile semiconductor memories and large-capacityDRAMs. The ferroelectric film in the semiconductor device may be any offilms comprised of a dielectric material having a high dielectricconstant, and may include, e.g., ferroelectric materials having aperovskite crystalline structure.

The dielectric material may include lead titanate zirconate Pb(Zr,Ti)O₃(abbreviated “PZT”), barium strontium titanate (Ba,Sr)TiO₃ (abbreviated“BST”), and niobium strontium bismuth tantalate (SrBi₂(Nb,Ta)₂O₉ (called“Y1 system”). These materials can be formed into films by chemical vapordeposition (CVD), the sol-gel method, or sputtering.

An example of the resin-encapsulated semiconductor apparatus of thepresent invention will be described below, taking as an example alead-on-chip type (“LOC type”) resin-encapsulated semiconductorapparatus shown in FIG. 1. The resin-encapsulated semiconductorapparatus is by no means limited to the LOC type, and may be adifferent-type resin-encapsulated semiconductor apparatus such as achip-on-lead type (“COL type”).

The resin-encapsulated semiconductor apparatus of the present inventionhas a semiconductor device 1 having on at least part of its surface asurface-protective film 2 comprised of polyimide; an outer terminal 3;an adhesive member 4 which bonds the semiconductor device 1 and theouter terminal 3 through the surface-protective film 2; wiring 5 forachieving conduction between the semiconductor device 1 and the outerterminal 3; and a encapsulant medium 6 for encapsulating the entiresemiconductor device 1 and wiring 5. The surface-protective film 2 iscomprised of a polyimide obtained by heat-curing the polyimide precursorpreviously described. In the resin-encapsulated semiconductor apparatusshown in FIG. 1, the outer terminal 3 also serves as a lead frame.

An example of the process for fabricating the resin-encapsulatedsemiconductor apparatus of the present invention will be described belowwith reference to FIGS. 2A to 2F. FIGS. 2A to 2F show a process forfabricating the LOC type resin-encapsulated semiconductor apparatusshown in FIG. 1. The fabrication process of the present invention is notlimited to the fabrication of the LOC type resin-encapulatedsemiconductor apparatus, and may also be applied to the fabrication ofthe resin-encapsulated semiconductor apparatuses of the other type suchas COL type so long as they are resin-encapsulated semiconductorapparatuses obtained by previously bonding semiconductor devices andouter terminals (lead frames) and then encapsulating them with a moldingresin.

(1) Surface-protective Film Forming Step:

As shown in FIG. 2A, a surface-protective film 2 comprised of polyimideis formed on a silicon wafer 9 on which semiconductor device regions andwiring layers (not shown) have been built up. The surface-protectivefilm 2 may be formed by, e.g., a method in which the polyimide precursorcomposition previously described is coated on the wafer 9, followed byheat curing, and a method in which the polyimide precursor compositionpreviously molded in a filmy form is placed on the surface of the wafer9, followed by heat curing.

As previously described, in the surface-protective film 2, openings areformed at predetermined positions, and the surface of the semiconductordevice 1 is laid bare at the areas of bonding pad portions 7 andscribing regions 8. To form the surface-protective film 2 in a patternwith openings corresponding to the bonding pad areas 7 and scribingregions 8, wet etching may be used which is a method making use of aphotoresist and a polyimide etching solution, and besides aphoto-etching technique such as dry etching in which a patternedinorganic film or metal film is used as a mask and the polyimide filmlaid bare is removed by oxygen plasma. Alternatively, using a mask, thepolyimide precursor composition may be coated except at the portions ofthe regions 7 and 8, and thus the surface-protective film 2 can bepatterned.

The silicon wafer 9 on which the surface-protective film 2 has beenformed in this way is cut off at its scribing regions to obtain thesemiconductor device 1 (shown in FIG. 2B) having the surface-protectivefilm 2. Here, a process is described in which the silicon wafer 9 withthe surface-protective film 2 having been formed thereon is cut off toobtain the semiconductor device 1 having the surface-protective film 2.In the present invention, without limitation thereto, the silicon wafer9 may be cut off to obtain a semiconductor device 1 and thereafter thefilm of the polyimide precursor compositon may be formed on the surfaceof the semiconductor device 1 thus obtained, followed by heat curing toobtain the semiconductor device 1 having the surface-protective film 2.

(2) Device Mounting Step:

The outer terminal 3 and the semiconductor device 1 are bonded throughan adhesive member 4 to obtain an assembly comprised of, as shown inFIG. 2C, the semiconductor device 1 and the outer terminal 3 which arebonded through the surface-protective film 2 and the adhesive member 4.Subsequently, as shown in FIG. 2D, the semiconductor device 1 is wiredwith gold wires 5 across its bonding pad areas 7 and outer terminals 3by means of a wire bonder to ensure the conduction between thesemiconductor device 1 and the outer terminals 3.

(3) Sealing Step:

As shown in FIG. 2E, molding is applied u sing a silica-containing epoxyresin at a molding temperature of 180° C. and a molding pressure of 70kg/cm² to form an encapsulant member 6. Finally, the outer terminals 3are bent into the desired shape, to thus obtain the LOC typeresin-encapsulated semiconductor apparatus as shown in FIG. 2F.

The semiconductor device used in the resin-encapsulated semiconductorapparatus of the present invention will be described below. As anexample of the semiconductor device used in the resin-encapsulatedsemiconductor apparatus of the present invention, a ferroelectric memorycomprising a memory cell of one transistor/one capacitor is shown inFIG. 4 as a cross-section at its memory cell portion.

This ferroelectric memory, 40, is a laminate comprising a siliconsubstrate 41; formed on its surface, a CMOS (complementary metal oxidesemiconductor) transistor layer 42 consisting of a p- or n-type well421, a set of source 422 and drain 423, an oxide film 424, a gate 425and an insulating layer 426, and further formed on the surface of theinsulating layer 426 a capacitor 43 consisting of a lower electrodelayer 431, a ferroelectric film 432, an upper electrode layer 433, ametal wiring layer 434 and an insulating layer 435. Thus, the presentinvention is applied to the instance where the surface-protectivepolyimide film is formed on the surface of the laminate (inclusive ofthe semiconductor device) having the ferroelectric film 432 andthereafter the assembly formed is encapsulated with resin. In theexample shown in FIG. 4, the surface-protective polyimide film is soformed as to cover the metal wiring layer 434 and insulating layer 435of the capacitor 43.

As described above in detail, the resin-encapsulated ferroelectricdevice having the surface-protective polyimide film is provided by thepresent invention. Since the polyimide precursor is heat-cured at atemperature of from 230° C. to 300° C., the ferroelectric film may causeless deterioration of polarization characteristics. Also, since thepolyimide constituting the surface-protective film 2 has a glasstransition temperature of 240° C. or above and a Young's modulus of2,600 MPa or above, a resin-encapsulated semiconductor apparatus can beobtained which has a superior solder reflow resistance after being resinencapsulating and in which no peeling may occur at the interface betweenthe polyimide and the encapsulant resin at the time of refloing solder.Also, since the polyimide precursor composition is used which isheat-cured at a temperature higher than 300° C. but not higher than 350°C. for a heating time within 4 minutes and also the polyimide obtainedafter curing of which has a glass transition temperature of 260° C. orabove and a Young's modulus of 3,500 MPa or above, it is possible toobtain a resin-encapsulated semiconductor apparatus that may cause lessdeterioration of polarization characteristics of the ferroelectric filmand has a superior solder reflow resistance after resin encapsulatingand in which no peeling may occur at the interface between the polyimideand the sealing resin at the time of reflowing solder. Thus, accordingto the present invention, a resin-encapsulated semiconductor apparatuswith a high reliability can be obtained.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Examples of the present invention will be given below.

With respect to polyimide films used in the following Examples, theYoung's modulus and the glass transition temperature were measured usingpolyimide films separately prepared. More specifically, first, using ahot plate, a polyimide film was formed on a silicon wafer under the sameconditions as in each Example, and thereafter the polyimide film waspeeled off the wafer, followed by washing with water and then drying toobtain a polyimide film with a layer thickness of from 9 to 10 μm. Thispolyimide film was cut to make a test piece 25 mm long×5 mm wide. Usinga tensile tester AUTOGRAPH AG-100E (manufactured by ShimadzuCorporation), tensile load and elongation with respect to the film weremeasured under conditions of a rate of pulling of 1 mm/minute todetermine the Young's modulus. The polyimide film was also cut in 15 mmlong×5 mm wide to make a test piece. At a load of 2 g/f (about 4×10⁻²N/m²) in the elongation direction and a rate of temperature rise of 5°C./minutes, a thermal expansion curve obtained from thermomechanicalmeasurement using TA-1500 (manufactured by Shinku Riko ULVAC) wasprepared, and from this curve the glass transition temperature wasdetermined.

The solder reflow resistance of the resin-encapsulated semiconductorapparatus was measured in the following way. First, theresin-encapsulated semiconductor apparatus was moistened by leaving itfor 168 hours under the thermostatic hygrostatic conditions of 85° C.and 85%. The resin-encapsulated semiconductor apparatus thus moistenedwas heated to a maximum temperature of 240 to 250° C. for 10 seconds andthen left to cool to room temperature, and this step was repeatedlycarried out three times. Thereafter, using an ultrasonic flaw detector,any interfacial failure between the polyimide and the encapsulant resinwas non-destructively observed to examine the solder reflow resistanceof the surface-protective polyimide film. With regard to the temperatureprofile of an infrared solder reflowing furnace, the temperature profiledescribed in “Packaging Techniques for Surface Mount Type LSI Packagesand Improvement in Its Reliability”, p. 451 (compiled by Hitachi Ltd.,Semiconductor & Integrated Circuits Division, published 1988) wasfollowed, setting a maximum temperature at 240 to 245° C.

Viscosity of polyimide precursor solutions was measured at 25° C. usinga viscometer Model DVR-E (manufactured by K.K. Tokimec).

EXAMPLE 1

In a stream of nitrogen, 92.0 g (0.46 mol) of 4,4′-diaminodiphenyl etherand 9.12 g (0.44 mol) of 4-aminophenyl 4-amino-3-carbonamidophenyl etherwere dissolved in 1,580.2 g of N-methyl-2-pyrrolidone to prepare anamine solution. Next, keeping the temperature of this solution at about15° C., a mixture of 54.5 g (0.25 mol) of pyromellitic dianhydride and80.5 g (0.25 mol) of 3,3′,4,4′-benzophenonetetracarboxylic dianhydridewas added while stirring. After their addition was completed, thereaction mixture was further reacted while stirring at about 15° C. forabout 5 hours in an atmosphere of nitrogen, to obtain a polyimideprecursor composition solution with a viscosity of about 30 poises. Thepolyimide precursor composition solution thus obtained contains as thepolyimide precursor the polyamic acid represented by the followinggeneral formula (I).

Here, the polyamide acid of the present Example is a copolymer whereinR¹ is

In the formulas (XI) and (XII), the numerals in brackets indicate theratio of the numbers of repeating units in one molecule.

A wafer was prepared on which a semiconductor device comprising acapacitive insulation film formed using a ferroelectric material, asilicon nitride film formed on the outermost surface, and bonding padsfor ensuring conduction were formed.

On this wafer, a PIQ coupler available from Hitachi Chemical Co., Ltd.was spin-coated, followed by heating at 300° C. for 4 minutes in the airusing a hot-plate heating unit, and thereafter the above polyimideprecursor composition solution was further spin-coated thereon, followedby heating at 140° C. for 1 minute in an atmosphere of nitrogen usingthe hot-plate heating unit.

Next, a positive photoresist OFPR800, available from Tokyo Ohka KogyoCo., Ltd., was spin-coated thereon, followed by heating at 90° C. for 1minute using the hot-plate heating unit to form a resist film on thesurface of the polyimide precursor composition film. The resist filmformed was then exposed through a photomask and developed to form in theresist film the openings where the underlying polyimide precursor filmwas laid bare, followed by heating at 160° C. for 1 minute using thehot-plate heating unit.

Next, using the resist developing solution aqueous alkali solution as itwas, the polyimide precursor composition film was etched to formopenings in the polyimide precursor composition film at its portionscorresponding to the resist openings. Then the resist film was removedusing a resist removing solution and a rinsing solution for exclusiveuse, and the polyimide precursor composition film was washed with water,followed by heating at 230° C. for 4 minutes and at 300° C. for 8 hoursto make the polyimide precursor into an imide to form on the devicesurface a surface-protective polyimide film having openings at thebonding pad portions. The polyimide film thus formed was in a layerthickness of 2.3 μm. The Young's modulus and glass transitiontemperature of the polyimide film were measured in the manner asdescribed above, to reveal that they were about 3,700 MPa and about 300°C., respectively.

Thereafter, using the polyimide film as a mask, the silicon nitride filmcovering the bonding pad portions was dry-etched with a mixed gas of 94%CF₄ and 6% O₂ to lay the aluminum electrode bare at the bonding padportions.

At this stage, as electrical characteristics of the device, the rate ofresidual polarization of the ferroelectric film was measured to findthat it was in a value only decreased by 5% compared with the rate ofresidual polarization of the initial ferroelectric film before the PIQcoupler treatment.

Next, this wafer with films thus processed was cut off at the scribingregions to obtain a semiconductor device having the surface-protectivefilm. This semiconductor device was secured to a lead frame in the stepof die bonding, and thereafter the semiconductor device was wired withgold wires across the bonding pad portions and outer terminals. Thedevice thus wired was further encapsulated with a silica-containingbiphenyl type epoxy resin available from Hitachi Chemical Co., Ltd. at amolding temperature of 180° C. and a molding pressure of 70 kg/cm² toform a resin-encapsulated portion. Finally, the outer terminals werebent into the predetermined shape to obtain a finished product of theresin-encapsulated semiconductor apparatus shown in FIG. 3.

The resin-encapsulated semiconductor apparatus thus obtained was testedto evaluate the solder reflow resistance in the manner as describedabove. As a result, neither peeling nor cracks occurred at the interfacebetween the surface-protective polyimide film and the encapsulant epoxyresin, thus a resin-encapsulated semiconductor apparatus with a highreliability was obtainable.

COMPARATIVE EXAMPLE 1

The same wafer as that in Example 1 was prepared, and on this wafer withthe semiconductor device a PIQ coupler available from Hitachi ChemicalCo., Ltd. was spin-coated, followed by heating at 300° C. for 4 minutesin the air using a hot-plate heating unit, and thereafter a polyimideprecursor solution PIQ-13, available from Hitachi Chemical Co., Ltd.,was spin-coated thereon, followed by heating at 140° C. for 1 minute inan atmosphere of nitrogen using the hot-plate heating unit, to form apolyimide precursor composition film.

Next, openings were formed in the polyimide precursor composition filmin the same manner as in Example 1, followed by heating at 230° C. for 4minutes in an atmosphere of nitrogen using the hot-plate heating unitand further followed by heating at 350° C. for 30 minutes in anatmosphere of nitrogen using a lateral type diffusion furnace. Thus, apolyimide film (PIQ-13 film) having openings at the bonding pad portionswas formed on the device surface. The PIQ-13 film thus formed was in alayer thickness of 2.3 μm. The Young's modulus and glass transitiontemperature of the PIQ-13 film were measured in the manner as describedabove, to reveal that they were about 3,300 MPa and about 310° C.,respectively.

Thereafter, in the same manner as in Example 1, the aluminum electrodewas laid bare at the bonding pad portions and the rate of residualpolarization of the ferroelectric film was measured to find that it wasin a value decreased by 60% compared with the value before the PIQcoupler treatment.

Next, a finished product of a resin-encapsulated semiconductor apparatuswas produced in the same manner as in Example 1, and its solder reflowresistance was evaluated in the same manner as in Example 1. As aresult, neither peeling nor cracks occurred at the interface between thesurface-protective polyimide film and the encapsulant epoxy resin, but,compared with the device of Example 1, the resin-encapsulatedsemiconductor apparatus obtained in the present Comparative Examplecaused so great a deterioration in polarization characteristics of theferroelectric film that it was unsuitable for practical use.

COMPARATIVE EXAMPLE 2

A surface-protective film was formed on the surface of the wafer withthe semiconductor device in the same manner as Comparative Example 1except that the heating time for the heat-curing of the polyimideprecursor composition film at 350° C. was shortened to 8 minutes. TheYoung's modulus and glass transition temperature of the PIQ-13 film inthe present Comparative Example were, like those in Comparative Example1, about 3,300 MPa and about 310° C., respectively. However, the rate ofresidual polarization of the ferroelectric film was in a value decreasedby 25% compared with the value before the PIQ coupler treatment, and,compared with the device of Example 1, the present device caused sogreat a deterioration in polarization characteristics that it wasunsuitable for practical use.

COMPARATIVE EXAMPLE 3

The same wafer as that in Example 1 was prepared, and on this wafer withthe semiconductor device a polyimide precursor composition PIX8803-9L,available from Hitachi Chemical Co., Ltd., was spin-coated, followed byheating at 100° C. for 1 minute and further at 230° C. for 8 minutes inan atmosphere of nitrogen using a hot-plate heating unit, to form apolyimide precursor composition film in a half-cured state.

Next, openings were formed in this polyimide precursor composition filmin the same manner as in Example 1, followed by heating at 230° C. for 4minutes in an atmosphere of nitrogen using the hot-plate heating unit toform a polyimide film (PIX8803-9L film) having openings at the bondingpad portions. The polyimide film thus formed was in a layer thickness of2.3 μm. The Young's modulus and glass transition temperature of thePIX8803-9L film were measured in the manner as described above, toreveal that they were about 2,000 MPa and about 200° C., respectively.

Next, using the polyimide film as a mask, the silicon nitride film wasdry-etched in the same manner as in Example 1 to lay the aluminumelectrode bare at the bonding pad portions, and the rate of residualpolarization of the ferroelectric film was measured to find that thedifference between the value obtained and the value before the coatingof the polyimide precursor composition was within 1%, showing almost nodeterioration of characteristics.

Next, a finished product of a resin-encapsulated semiconductor apparatuswas produced in the same manner as in Example 1, and its solder reflowresistance was evaluated in the same manner as in Example 1. As aresult, peeling was seen to occur over the whole interface between thesurface-protective polyimide film and the encapsulant epoxy resin, andonly a resin-encapsulated semiconductor apparatus with an extremely lowreliability was obtainable.

EXAMPLE 2

In a stream of nitrogen, 88.0 g (0.44 mol) of 4,4′-diaminodiphenyl etherand 13.68 g (0.06 mol) of 4-aminophenyl 4-amino-3-carbonamidophenylether were dissolved in 1,584 g of N-methyl-2-pyrrolidone to prepare anamine solution. Next, keeping the temperature of this solution at about15° C., a mixture of 54.5 g (0.25 mol) of pyromellitic dianhydride and80.5 g (0.25 mol) of 3,3′,4,4′-benzophenonetetracarboxylic dianhydridewas added while stirring. After their addition was completed, themixture was further reacted while stirring at about 15° C. for about 5hours in an atmosphere of nitrogen, to obtain a polyimide precursorcomposition solution with a viscosity of about 30 poises. The polyimideprecursor composition solution thus obtained contains as the polyimideprecursor the same polyamic acid copolymer as that of Example 1 exceptthat R² is in a different copolymerization ratio. The R² in the presentExample is

In the formula (XIII), the numeral in brackets indicates the ratio ofthe numbers of repeating units in one molecule.

Next, the same wafer as that in Example 1 was prepared, and on thesurface of this wafer with the semiconductor device a PIQ coupleravailable from Hitachi Chemical Co., Ltd. was spin-coated, followed byheating at 260° C. for 4 minutes in the air using a hot-plate heatingunit, and thereafter the above polyimide precursor composition solutionwas further spin-coated thereon, followed by heating at 140° C. for 1minute in an atmosphere of nitrogen using the hot-plate heating unit.Thus, a polyimide precursor composition film was formed.

Openings were provided in this composition film in the same manner as inExample 1, followed by heating at 230° C. for 4 minutes and at 260° C.for 8 hours to make the polyimide precursor into an imide to form on thedevice surface a surface-protective polyimide film having openings atthe bonding pad portions. The polyimide film thus formed was in a layerthickness of 2.3 μm. The Young's modulus and glass transitiontemperature of the polyimide film were measured in the manner asdescribed above, to reveal that they were about 3,300 MPa and about 300°C., respectively.

At this stage, the rate of residual polarization of the ferroelectricfilm was measured to find that it was in a value only decreased by about2% compared with the rate of residual polarization of the initialferroelectric film before the PIQ coupler treatment.

Next, a finished product of a resin-encapsulated semiconductor apparatuswas produced in the same manner as in Example 1, and the finishedproduct thus obtained was tested to evaluate the solder reflowresistance. As a result, neither peeling nor cracks occurred at theinterface between the surface-protective polyimide film and theencapsulant epoxy resin, thus a resin-encapsulated semiconductorapparatus with a high reliability was obtainable.

EXAMPLE 3

In a stream of nitrogen, 90.0 g (0.45 mol) of 4,4′-diaminodiphenyl etherand 9.6 g (0.05 mol) of bis(3-aminopropyl)tetramethyldisiloxane weredissolved in 1,584 g of N-methyl-2-pyrrolidone to prepare an aminesolution. Next, keeping the temperature of this solution at about 15°C., 147 g (0.5 mol) of 3,3′,4,4′-biphenyltetracarboxylic dianhydride wasadded while stirring. After its addition was completed, the reactionmixture was further reacted while stirring at about 15° C. for about 5hours in an atmosphere of nitrogen, to obtain a polyimide precursorcomposition solution with a viscosity of about 50 poises. The polyimideprecursor composition solution thus obtained contains as the polyimideprecursor a polyamic acid copolymer comprised of a first repeating unitrepresented by the following general formula (XIV) and a secondrepeating unit represented by the following general formula (XV). Here,the proportion of the number of the second repeating unit to the totalnumber of the first repeating unit and second repeating unit is 10%.

Next, the same wafer as that in Example 1 was prepared, and on thesurface of this wafer with the semiconductor device a PIQ coupleravailable from Hitachi Chemical Co., Ltd. was spin-coated, followed byheating at 260° C. for 4 minutes in the air using a hot-plate heatingunit, and thereafter the above polyimide precursor composition solutionwas further spin-coated thereon, followed by heating at 140° C. for 1minute in an atmosphere of nitrogen using the hot-plate heating unit.Thus, a polyimide precursor composition film was formed.

Openings were provided in this composition film in the same manner as inExample 1, followed by heating at 230° C. for 4 minutes and at 260° C.for 8 minutes to make the polyimide precursor into an imide to form onthe device surface a surface-protective polyimide film having openingsat the bonding pad portions. The polyimide film thus formed was in alayer thickness of 2.3 μm. The Young's modulus and glass transitiontemperature of the polyimide film were measured in the manner asdescribed above, to reveal that they were about 3,000 MPa and about 255°C., respectively.

At this stage, the rate of residual polarization of the ferroelectricfilm was measured to find that it was in a value only decreased by about2% compared with the rate of residual polarization of the initialferroelectric film before the PIQ coupler treatment.

Next, a finished product of a resin-encapsulated semiconductor apparatuswas produced in the same manner as in Example 1, and the finishedproduct thus obtained was tested to evaluate the solder reflowresistance. As a result, neither peeling nor cracks occurred at theinterface between the surface-protective polyimide film and the sealingepoxy resin, thus a resin-encapsulated semiconductor apparatus with ahigh reliability was obtainable.

EXAMPLE 4

In a stream of nitrogen, 103.0 g (0.5 mol) of 3,3′-dimethylbenzidine wasdissolved in 1,474.5 g of N-methyl-2-pyrrolidone, and 155.0 g (0.5 mol)of 4,4′-oxyphthalic dianhydride was added while stirring. After itsaddition was completed, the reaction mixture was further reacted whilestirring at about 15° C. for about 5 hours in an atmosphere of nitrogen,to obtain a polyimide precursor composition solution with a viscosity ofabout 30 poises. The polyimide precursor composition solution thusobtained contains as the polyimide precursor a polyamide acid comprisedof a repeating unit represented by the following general formula (XVI):

Next, the same wafer as that in Example 1 was prepared, and on thesurface of this wafer with the semiconductor device a PIQ coupleravailable from Hitachi Chemical Co., Ltd. was spin-coated, followed byheating at 240° C. for 4 minutes in the air using a hot-plate heatingunit, and thereafter the above polyimide precursor composition solutionwas further spin-coated thereon, followed by heating at 140° C. for 1minute in an atmosphere of nitrogen using the hot-plate heating unit.Thus, a polyimide precursor composition film was formed.

Openings were provided in this composition film in the same manner as inExample 1, followed by heating at 230° C. for 4 minutes and at 240° C.for 10 minutes to make the polyimide precursor into an imide to form onthe device surface a surface-protective polyimide film having openingsat the bonding pad portions. The polyimide film thus formed was in alayer thickness of 2.3 μm. The Young's modulus and glass transitiontemperature of the polyimide film were measured in the manner asdescribed above, to reveal that they were about 4,000 MPa and about 250°C., respectively.

At this stage, the rate of residual polarization of the ferroelectricfilm was measured to find that it was in a value decreased by about 1%at most, compared with the rate of residual polarization of the initialferroelectric film before the PIQ coupler treatment.

Next, a finished product of a resin-encapsulated semiconductor apparatuswas produced in the same manner as in Example 1, and the finishedproduct thus obtained was tested to evaluate the solder reflowresistance. As a result, neither peeling nor cracks occurred at theinterface between the surface-protective polyimide film and theencapsulant epoxy resin, thus a resin-encapsulated semiconductorapparatus with a high reliability was obtainable.

EXAMPLE 5

In the polyimide precursor composition solution synthesized in Example1, 20.0 parts by weight of 3-(N,N-dimethylamino)propyl methacrylate and5.0 parts by weight of 2,6-di(p-azidobenzal)-4-carboxycyclohexanonebased on 100 parts by weight of the polyimide precursor polymer wereadded and dissolved to obtain a photosensitive composition solution.

Next, the same wafer as that in Example 1 was prepared, and on thesurface of this wafer with the semiconductor device a PIQ coupleravailable from Hitachi Chemical Co., Ltd. was spin-coated, followed byheating at 250° C. for 4 minutes in the air using a hot-plate heatingunit, and thereafter the above photosensitive composition solution wasfurther spin-coated thereon, followed by heating at 85° C. for 1 minuteand subsequently at 95° C. for 1 minute in an atmosphere of nitrogenusing a hot-plate heating unit. Thus, a polyimide precursor compositionfilm was formed.

This composition film was exposed through a photomask and then developedwith a mixture solution comprised of 4 parts by volume ofN-methyl-2-pyrrolidone and 1 part by volume of ethanol, followed byrinsing with ethanol to form openings at the bonding pad portions. Next,the film was heated successively at 130° C. for 4 minutes, at 170° C.for 4 minutes, at 220° C. for 4 minutes and at 250° C. for 8 minutesusing the hot-plate heating unit to cause the polyimide precursor tocure to form a polyimide film having openings at the bonding padportions. The polyimide film thus formed was in a layer thickness of 2.3μm. The Young's modulus and glass transition temperature of thepolyimide film were also measured to reveal that they were about 3,300MPa and about 300° C., respectively.

At this stage, the rate of residual polarization of the ferroelectricfilm was measured to find that it was in a value decreased by about 1%at most, compared with the rate of residual polarization of the initialferroelectric film before the PIQ coupler treatment.

Next, a finished product of a resin-encapsulated semiconductor apparatuswas produced in the same manner as in Example 1, and the finishedproduct thus obtained was tested to evaluate the solder reflowresistance. As a result, neither peeling nor cracks occurred at theinterface between the surface-protective polyimide film and theencapsulant epoxy resin, thus a resin-encapsulated semiconductorapparatus with a high reliability was obtainable.

EXAMPLE 6

In the polyimide precursor composition solution synthesized in Example2, 20.0 parts by weight of 3-(N,N-dimethylamino)propyl methacrylate, 3.0parts by weight of Michler's ketone and 3.0 parts by weight ofbis-4,4′-diethylaminobenzophenone based on 100 parts by weight of thepolyimide precursor polymer were added and dissolved to obtain aphotosensitive composition solution.

Next, the same wafer as that in Example 1 was prepared, and on thesurface of this wafer with the semiconductor device a PIQ coupleravailable from Hitachi Chemical Co., Ltd. was spin-coated, followed byheating at 270° C. for 4 minutes in the air using a hot-plate heatingunit, and thereafter the above photosensitive composition solution wasfurther spin-coated thereon, followed by heating at 85° C. for 1 minuteand subsequently at 95° C. for 1 minute in an atmosphere of nitrogenusing a hot-plate heating unit. Thus, a polyimide precursor compositionfilm was formed.

Openings were formed in this composition film in the same manner as inExample 5, followed by heating successively at 130° C. for 4 minutes, at170° C. for 4 minutes, at 220° C. for 4 minutes and at 270° C. for 8minutes using the hot-plate heating unit to cause the polyimideprecursor to cure to form a polyimide film having openings at thebonding pad portions. The polyimide film thus formed was in a layerthickness of 2.3 μm. The Young's modulus and glass transitiontemperature of the polyimide film were also measured to reveal that theywere about 3,300 MPa and about 300° C., respectively.

At this stage, the rate of residual polarization of the ferroelectricfilm was measured to find that it was in a value decreased by about 1%at most, compared with the rate of residual polarization of the initialferroelectric film before the PIQ coupler treatment.

Next, a finished product of a resin-encapsulated semiconductor apparatuswas produced in the same manner as in Example 1, and the finishedproduct thus obtained was tested to evaluate the solder reflowresistance. As a result, neither peeling nor cracks occurred at theinterface between the surface-protective polyimide film and theencapsulant epoxy resin, thus a resin-encapsulated semiconductorapparatus with a high reliability was obtainable.

EXAMPLE 7

In the polyimide precursor composition solution synthesized in Example3, 20.0 parts by weight of 3-(N,N-dimethylamino)propyl methacrylate and5.0 parts by weight of 2,6-di(p-azidobezal)-4-carboxycyclohexanone basedon 100 parts by weight of the polyimide precursor polymer were added anddissolved to obtain a photosensitive composition solution.

Next, the same wafer as that in Example 1 was prepared, and on thesurface of this wafer with the semiconductor device a PIQ coupleravailable from Hitachi Chemical Co., Ltd. was spin-coated, followed byheating at 260° C. for 4 minutes in the air using a hot-plate heatingunit, and thereafter the above photosensitive composition solution wasfurther spin-coated thereon, followed by heating at 85° C. for 1 minuteand subsequently at 95° C. for 1 minute in an atmosphere of nitrogenusing a hot-plate heating unit. Thus, a polyimide precursor compositionfilm was formed.

Openings were formed in this composition film in the same manner as inExample 5, followed by heating successively at 130° C. for 4 minutes, at170° C. for 4 minutes, at 220° C. for 4 minutes and at 260° C. for 8minutes using the hot-plate heating unit to cause the polyimideprecursor to cure to form a polyimide film having openings at thebonding pad portions. The polyimide film thus formed was in a layerthickness of 2.3 μm. The Young's modulus and glass transitiontemperature of the polyimide film were also measured to reveal that theywere about 3,000 MPa and about 260° C., respectively.

At this stage, the rate of residual polarization of the ferroelectricfilm was measured to find that it was in a value decreased by about 2%at most, compared with the rate of residual polarization of the initialferroelectric film before the PIQ coupler treatment.

Next, a finished product of a resin-encapsulated semiconductor apparatuswas produced in the same manner as in Example 1, and the finishedproduct thus obtained was tested to evaluate the solder reflowresistance. As a result, neither peeling nor cracks occurred at theinterface between the surface-protective polyimide film and theencapsulant epoxy resin, thus a resin-encapsulated semiconductorapparatus with a high reliability was obtainable.

EXAMPLE 8

In the polyimide precursor composition solution synthesized in Example4, 20.0 parts by weight of 3-(N,N-dimethylamino)propyl methacrylate, 3.0parts by weight of Michler's ketone and 3.0 parts by weight ofbis-4,4′-diethylaminobenzophenone based on 100 parts by weight of thepolyimide precursor polymer were added and dissolved to obtain aphotosensitive composition solution.

Next, the same wafer as that in Example 1 was prepared, and the surfaceof this wafer with the semiconductor device was treated with the PIQcoupler in the same manner as in Example 5, and thereafter the abovephotosensitive composition solution was further spin-coated thereonfollowed by heating, in the same manner as in Example 5. Thus, apolyimide precursor composition film was formed.

Openings were formed in this composition film in the same manner as inExample 5, and the film was heat-cured in the same manner as in Example5 to form a polyimide film. The polyimide film thus formed was in alayer thickness of 2.3 μm. The Young's modulus and glass transitiontemperature of the polyimide film were measured to reveal that they wereabout 4,000 MPa and about 250° C., respectively.

At this stage, the rate of residual polarization of the ferroelectricfilm was measured to find that it was in a value decreased by about 1%at most, compared with the rate of residual polarization of the initialferroelectric film before the PIQ coupler treatment.

Next, a finished product of a resin-encapsulated semiconductor apparatuswas produced in the same manner as in Example 1, and the finishedproduct thus obtained was tested to evaluate the solder reflowresistance. As a result, neither peeling nor cracks occurred at theinterface between the surface-protective polyimide film and theencapsulant epoxy resin, thus a resin-encapsulated semiconductorapparatus with a high reliability was obtainable.

EXAMPLE 9

The same wafer as that in Example 1 was prepared, and on the surface ofthis wafer with the semiconductor device a PIQ coupler available fromHitachi Chemical Co., Ltd. was spin-coated, followed by heating at 230°C. for 4 minutes in the air using a hot-plate heating unit, andthereafter the polyimide precursor composition solution synthesized inExample 4 was further spin-coated thereon, followed by heating at 140°C. for 1 minute in an atmosphere of nitrogen using a hot-plate heatingunit. Thus, a polyimide precursor composition film was formed.

Openings were formed in this composition film in the same manner as inExample 4, followed by heating at 200° C. for 4 minutes and subsequentlyat 230° C. for 10 minutes using the hot-plate heating unit to cause thepolyimide precursor to cure to form a surface-protective polyimide filmhaving openings at the bonding pad portions. The polyimide film thusformed was in a layer thickness of 2.3 μm. The Young's modulus and glasstransition temperature of the polyimide film were also measured toreveal that they were about 4,000 MPa and about 250° C., respectively.

At this stage, the rate of residual polarization of the ferroelectricfilm was measured to find that, like Example 4, the deterioration due toheat treatment was about 1% at most. A finished product of aresin-encapsulated semiconductor apparatus was produced in the samemanner as in Example 1, and the finished product thus obtained had asolder reflow resistance as good as that in Example 4.

EXAMPLE 10

In the polyimide precursor composition solution synthesized in Example4, 20.0 parts by weight of 3-(N,N-dimethylamino)propyl methacrylate and6.0 parts by weight of Michler's ketone based on 100 parts by weight ofthe polyimide precursor polymer were added and dissolved to obtain aphotosensitive composition solution.

Next, the same wafer as that in Example 1 was prepared, and the surfaceof this wafer with the semiconductor device was treated with the PIQcoupler in the same manner as in Example 9, and thereafter the abovephotosensitive composition solution was further spin-coated thereon,followed by heating at 85° C. for 1 minute and subsequently at 95° C.for 1 minute in an atmosphere of nitrogen using a hot-plate heatingunit. Thus, a polyimide precursor composition film was formed.

Openings were formed in this composition film in the same manner as inExample 5, followed by heating successively at 130° C. for 4 minutes, at170° C. for 4 minutes, at 200° C. for 4 minutes and at 230° C. for 10minutes using the hot-plate heating unit to cause the polyimideprecursor to cure to form a polyimide film having openings at thebonding pad portions. The polyimide film thus formed was in a layerthickness of 2.3 μm. The Young's modulus and glass transitiontemperature of the polyimide film were also measured to reveal that theywere about 4,000 MPa and about 250° C., respectively.

At this stage, the rate of residual polarization of the ferroelectricfilm was measured to find that, like Example 4, the deterioration due toheat treatment was about 1% at most. A finished product of aresin-encapsulated semiconductor apparatus was produced in the samemanner as in Example 1, and the finished product thus obtained had asolder reflow resistance as good as that in Example 4.

EXAMPLE 11

In a stream of nitrogen, 95.4 g (0.45 mol) of 3,3′-dimethylbenzidine and9.6 g (0.05 mol) of bis(3-aminopropyl)tetramethyldisiloxane weredissolved in 1,040 g of N-methyl-2-pyrrolidone to prepare an aminesolution. Next, keeping the temperature of this solution at about 15°C., 155.0 g (0.5 mol) of 4,4′-oxyphthalic dianhydride was added whilestirring, and thereafter the reaction mixture was further stirred atabout 15° C. for about 8 hours in an atmosphere of nitrogen, to obtain apolyimide precursor solution with a viscosity of about 30 poises.

The polyimide precursor composition solution thus obtained contains asthe polyimide precursor a polyamic acid copolymer comprised of a firstrepeating unit represented by the above general formula (XVI) and asecond repeating unit represented by the following general formula(XIX):

Here, the number of the second repeating unit comprised about 10% of thewhole. Using the polyimide precursor solution thus obtained, aphotosensitive composition solution was prepared in the same manner asin Example 5.

Next, the same wafer as that in Example 1 was prepared, and on thesurface of this wafer the photosensitive composition solution wasspin-coated, followed by heating at 85° C. for 1 minute and subsequentlyat 95° C. for 1 minute in an atmosphere of nitrogen using a hot-plateheating unit. Thereafter, the composition film formed was exposedthrough a photomask and then developed with a mixture solution comprisedof 4 parts by volume of N-methyl-2-pyrrolidone and 1 part by volume ofethanol, followed by rinsing with ethanol to form openings where thebonding pad portions were uncovered. Subsequently, the film was heatedsuccessively at 130° C. for 3 minutes, at 170° C. for 3 minutes, at 220°C. for 3 minutes and at 300° C. for 6 minutes using the hot-plateheating unit to cause the polyimide precursor to cure. The polyimidefilm thus formed was in a layer thickness of 2.3 μm. The Young's modulusand glass transition temperature of the polyimide film were about 4,000MPa and about 260° C., respectively.

At this stage, the rate of residual polarization of the ferroelectricfilm was measured to find that it was in a value decreased by about 1%at most, compared with the rate of residual polarization of the initialferroelectric film before the coating of the polyimide precursorsolution.

Next, a finished product of a resin-encapsulated semiconductor apparatuswas produced in the same manner as in Example 1, and thereafter wastested to evaluate the solder reflow resistance in the same manner as inExample 1. As a result, like Example 1, the product had a highreliability.

EXAMPLE 12

In the present Example, a resin-encapsulated semiconductor apparatus wasfabricated in the same manner as in Example 11 except that the heatingafter the formation of openings was carried out successively at 130° C.for 3 minutes, at 170° C. for 3 minutes, at 220° C. for 3 minutes and at350° C. for 2 minutes. The Young's modulus and glass transitiontemperature of the polyimide film thus formed were the same as those inExample 11.

At this stage, the rate of residual polarization of the ferroelectricfilm was measured to find that it was in a value decreased by about 5%at most, compared with the rate of residual polarization of the initialferroelectric film before the coating of the polyimide precursorsolution.

Next, a finished product of a resin-encapsulated semiconductor apparatuswas produced in the same manner as in Example 1, and thereafter wastested to evaluate the solder reflow resistance in the same manner as inExample 1. As a result, like Example 1, the product had a highreliability.

What is claimed is:
 1. A resin-encapsulated semiconductor apparatuscomprising a semiconductor device having a ferroelectric film and asurface-protective film, and an encapsulant member comprising a resin;wherein said ferroelectric film is made of a dielectric material havinga Perovskite crystal structure, and is a capacity insulation film of acapacitor of said semiconductor device; said surface-protective filmcovers a surface of said semiconductor device fixed on a lead frame,except for a bonding pad portion and a scribe area; said bonding padportion of said semiconductor device and terminal of said lead frame areconnected be bonding wire and; said semiconductor device and said leadframe are encapsulated with said encapsulant member.
 2. Arein-encapsulated semiconductor apparatus comprising a semiconductordevice having a ferroelectric film and a surface-protective film, and anencapsulant member comprising a resin; wherein said ferroelectric filmis made of a dielectric material having a Perovskite crystal structure,and is a capacity insulation film of a capacitor of said semiconductordevice; said surface-protective film covers a surface of saidsemiconductor device except for a bonding pad portion and a scribe area;a lead frame is fixed on said surface-protective film; and said bondingpad portion of said semiconductor device and a terminal of said leadframe are connected by bonding wire; and said semiconductor device andsaid lead frame are encapsulated with said encapsulated member.
 3. Arein-encapsulated semiconductor apparatus comprising a semiconductordevice having a ferroelectric film and a surface-protective film, and anencapsulant member comprising a resin, wherein said ferroelectric filmis made of a dielectric material having a Perovskite crystal structure,and is a capacity insulation film of a capacitor of said semiconductordevice; said surface-protective film covers an active area of saidsemiconductor device; said semiconductor device is fixed on a leadframe; a bonding pad of said semiconductor device and terminal of saidlead frame are connected by bonding wire; and said semiconductor deviceand said lead frame are encapsulated with said encapsulant member.
 4. Arein-encapsulated semiconductor apparatus comprising a semiconductordevice having a ferroelectric film and a surface-protective film, and anencapsulant member comprising a resin, wherein said ferroelectric filmis made of a dielectric material having a Perovskite crystal structure,and is a capacity insulation film of a capacitor of said semiconductordevice; a lead frame is fixed on said surface-protective film coveringan active area of said semiconductor device; a bonding pad portion ofsaid semiconductor device and a terminal of said lead frame areconnected by bonding wire; and said semiconductor device and said leadframe are encapsulated with an encapsulant member.
 5. Aresin-encapsulated semiconductor apparatus according to claim 1, whereinsaid surface-protective film comprises a polyimide.
 6. Aresin-encapsulated semiconductor apparatus according to claim 1, saidsurface-protective film has a glass transition temperature of from 240°C to 400° C.
 7. A resin-encapsulated semi-conductor apparatus accordingto claim 1, wherein said surface-protective film has a Young's modulusof from 2600 MPa to 6 GPa.
 8. A resin-encapsulated semiconductorapparatus according to claim 1, wherein said surface-protective film hasa glass transition temperature of from 240° C to 400° C and has aYoung's modulus of from 2600 MPa to 6 GPa.
 9. A resin-encapsulatedsemi-conductor apparatus according to claim 5, wherein said polyimidehas a glass transition temperature of from 240° C to 400° C.
 10. Aresin-encapsulated semiconductor apparatus according to claim 5, whereinsaid polyimide has a Young's modulus of from 2600 MPa to 6 GPa.
 11. Aresin-encapsulated semiconductor apparatus according to claim 5, whereinsaid polyimide has a glass transition temperature of from 240° C to 400°and has a Young's modulus of 2600 MPa to 6 GPa.
 12. A resin-encapsulatedsemiconductor apparatus according to claim 1, wherein said encapsulantcomprises silica and an epoxy resin.
 13. A resin-encapsulatedsemiconductor apparatus according to claim 1, wherein at least one ofelectrodes of said capacitor having said ferroelectric film therebetweencomprises a precious metal.
 14. A resin-encapsulated semiconductorapparatus according to claim 1, wherein at lease one of electrodes ofsaid capacitors having said ferroelectric film therebetween comprises ametal oxide or an oxidizing electrode.
 15. A resin-encapsulatedsemiconductor apparatus according to claim 14, wherein said at least oneof electrodes comprises a metal oxide, and said metal oxide is strontiumruthenium oxide or iridium oxide.
 16. A resin-encapsulated semiconductorapparatus according to claim 14, wherein said oxidizing electrodecomprises iridium.
 17. A resin-encapsulated semiconductor apparatusaccording to claim 13, wherein said precious metal comprises platinum.18. A resin-encapsulated semiconductor apparatus according to claim 2,wherein said surface-protective film comprises a polyimide.
 19. Aresin-encapsulated semiconductor apparatus according to claim 2, whereinsaid surface-protective film has a glass transition temperature of from240° C to 400° C.
 20. A resin-encapsulated semiconductor apparatusaccording to claim 2, wherein said surface-protective film has a Young'smodulus of from 2600 MPa to 6 GPa.
 21. A resin-encapsulatedsemiconductor apparatus according to claim 2, wherein saidsurface-protective film has a glass transition temperature of from 240°C to 400° C and has a Young's modulus of from 2600 MPa to 6 GPa.
 22. Aresin-encapsulated semiconductor apparatus according to claim 18,wherein said polyimide has a glass transition temperature of from 240°C. to 400° C.
 23. A resin-encapsulated semiconductor apparatus accordingto claim 18, wherein said polyimide has a Young's modulus of from 2600MPa to 6 GPa.
 24. A resin-encapsulated semiconductor apparatus accordingto claim 18, wherein said polyimide has a glass transition temperatureof from 240° C. to 400° C. and has a Young's modulus of from 2600 MPa to6 GPa.
 25. A resin-encapsulated semiconductor apparatus according toclaim 2, wherein said encapsulant comprises silica and an epoxy resin.26. A resin-encapsulated semiconductor apparatus according to claim 2,wherein at least one of electrodes of said capacitor having aferroelectric film therebetween comprises a precious metal.
 27. Aresin-encapsulated semiconductor apparatus according to claim 2, whereinat least on of electrode of said capacitor having said ferroelectricfilm therebetween comprises a metal oxide or an oxidizing electrode. 28.A resin-encapsulated semiconductor apparatus according to claim 27,wherein at least one of electrodes comprises a metal oxide, and saidmetal oxide is strontium ruthenium oxide or iridium oxide.
 29. Aresin-encapsulated semiconductor apparatus according to claim 27,wherein said oxidizing electrode comprises iridium.
 30. Aresin-encapsulated semiconductor apparatus according to claim 26,wherein said precious metal comprises platinum.